There is the "night stalker" richard ramirez and maybe the cult killings in matamoros, mexico which caused panic in the 80's. http://www.markkilroyfoundation.org/about-us.html People who deeply believe in serving evil are just as much of a threat.
In Christian theology "Satan" is the fallen Lucifer; with Lucifer, "the Shining One," being a blessed archangel, the most elect of the elect of God. Lucifer's realm was earth. When Lucifer's pride led him to mount in effect a cosmic civil war, he came up wanting, and his ass was cast down to his realm, Earth; becoming Satan in the act. I hold no religious beliefs but it is interesting that Satan has been associated with earthly, corporeal, sensual existence. Much of the early Church transcribed native practices in the lands over which it had or gained dominion to be "Satanic" in origin, and these would include animistic beliefs and rites, springing from a close association, in many places, with worship of the Great Goddess, feminine principle, Gaia/Earth, however you would frame it; all of which continues today, in many parts of the world, including Europe (one need only go to the Baltics in May to see the persistence of "fertility festivals"). Personally, my impression of satanists, at least in the Anton LaVey line, is that they are in essence a bunch of selfish pricks - "me first, me above all else," encapsulated in the creed: Not who'd I'd choose to have a pint with, but afraid? No.
I don't know , maybe there are some scary satanists hiding somewhere, but most people who I have met who proclaim they are satanists are dorks
Yes but what IF god is really the bad guy here. I'm not sure I approve of his existence. I mean is it possible we have all been bamboozled for all these thousands of years? How about a little sympathy for the devil?